Herbicide resistant plants may reduce the need for tillage to control weeds thereby effectively reducing costs to the growers. Development of crops with increased herbicide resistance has been a major breakthrough in current agriculture practices as it has provided farmers with new weed control options.
One herbicide which is the subject of much investigation in this regard is N-phosphonomethylglycine, commonly referred to as glyphosate. Glyphosate inhibits the shikimic acid pathway which leads to the biosynthesis of aromatic compounds including amino acids, hormones and vitamins. Specifically, glyphosate curbs the conversion of phosphoenolpyruvic acid (PEP) and 3-phosphoshikimic acid to 5-enolpyravyl-3-phosphoshikimic acid by inhibiting the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (referred to as EPSPS). Plant genetic engineering methods have been used to modify EPSP synthase DNA and the encoded proteins, and to transfer these molecules into plants of agronomic importance. Variants of class I EPSPS have been isolated (Pro-Ser, U.S. Pat. No. 4,769,061; Gly-Ala, U.S. Pat. No. 4,971,908; Gly-Ala, Gly-Asp, U.S. Pat. No. 5,310,667; Gly-Ala, Ala-Thr, U.S. Pat. No. 5,866,775) that cause resistance to glyphosate. However, many EPSPS variants are not effective enzymes for use in plants (Padgette et. Al., in “Herbicide-resistant Crops”, Chapter 4 pp. 53-83. ed. Stephen Duke, Lewis Pub, CRC Press Boca Raton, Fla. 1996). One class I EPSPS variant, T-102-I/P-106-S(TIPS) that is operably linked to a heterologous promoter has been shown to provide glyphosate (N-phosphonomethylglycine) resistance to transgenic maize plants (U.S. Pat. No. 6,040,497).
There remains a need for the development of herbicide-resistant crops and for glyphosate resistant crops in particular. There is also a need to develop herbicide-resistant plants of agronomic value that contain mutated genes obtained through gene editing wherein the mutation of the gene results in herbicide resistance.
Compositions and methods for producing mutant plants that exhibit herbicide resistance, and glyphosate resistance specifically, are provided.